Jib crane



-De.30,v1969 v J15.TH oNkqol q 3,486,635

JIB CRANE Filed Feb. 7, 1968 2 Sheets-Sheet 1 if 7 l3 I2 I 6 K) 9 l6 INVENTOR JOHN STEVENSON THOMSON bY ,JA

ATTORNEYS Dec. 30, 1969 J, 5, THOMSON 3,486,635

JIB CRANE Filed Feb. 7, 1968 2 Sheets-Sheet 2 INVENTOR JOHN STEVENSON THOMSON BY 4- 7M ATTORNEYS United States Patent 3,486,635 JIB CRANE John Stevenson Thomson, 104 Forsyth St., Greenock, Renfrewshire, Scotland Filed Feb. 7, 1968, Ser. No. 703,641 Claims priority, application Great Britain, Feb. 10, 1967,

Int. Cl. B66c 23/06, 23/52; B66i 23/62 US. Cl. 212-58 8 Claims ABSTRACT OF THE DISCLOSURE A jib crane has a jib mounted at one end on the deck for lufiing and slewing and carries an outrigger that extends laterally in opposite directions from the free end of the jib. A fixed cross member transverse to the jib is spaced above the lower end of the jib. Equal numbers of pulleys are spaced along the outrigger on opposite sides of the vertical plane of the jib, and the same is true for the cross member. Two ropes have ends wound around winch winding drums, one of the ropes being reeved back and forth about the pulleys on one side of the vertical plane while the other rope is similarly reeved about the pulleys on the other side of the vertical plane so as to form between the outrigger and the cross member a plurality of rope reaches substantially traversing in zigzag manner the space defined by the ends of the outrigger and cross member and including reaches that diverge from the outrigger toward the cross member.

This invention relates to jib cranes and has particular, but not exclusive, reference to ships cranes.

According to the invention a jib crane includes a jib mounted at one end on a base for lufiing and slewing movements relative to the base, a first anchorage on the jib adjacent the free end thereof and extending laterally on both sides thereof, a second anchorage fixed relative to said base and disposed transversely of the jib above the mounted end of the jib, pulley means anchored to said anchorages at spaced intervals therealong, winch means and ropes operatively associated with winch means and cooperating with said pulley means to effect said luffing and slewing movements, said ropes being reeved back and forth around and between the pulley means anchored to said first and second anchorages to form between said anchorages a plurality of rope reaches which are disposed on both sides of the vertical plane containing the longitudinal axis of the jib and which substantially tranverse in zig-zag manner the quadrilateral space defined 'by the ends of said anchorages, said pulley means being so spaced along said anchorages that the rope reaches on each side of said plane include reaches which diverge from each other from said first to said second anchorage.

Preferably, said ropes have their ends attached to said winch means in such a way as to elfect said lufling and slewing movements of the jib, the ropes passing from the winch means to and around appropriate pulleys of said pulley means on said second anchorage, wherefrom the ropes form said plurality of reaches between said anchorages.

In this specification the term pulley means is intended to include pulley blocks and like devices incorporating rope pulleys, and the term rope to include any loadsupporting flexible member adapted for passing around pulleys, winch drums, and the like.

An example of the invention will now be described, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a ships crane according to the invention, in which, for the sake of clarity, only simple means relating to the raising and lowering of loads is partially shown.

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FIG. 2 is a plan view corresponding to FIG. 1, but to a somewhat larger scale.

Referring to the drawings, the jib crane shown has its jib 1 provided at its heel with a pivot pin 2, by means of which the jib is pivotally mounted on a trunnion 3, so that the jib may define lufiing (raising or lowering) movement and slewing movement relative to a deck 4 upon which the trunnion is mounted.

A first anchorage for pulley blocks is secured to the jib near the free end thereof and consists of an outrigger 5 which extends laterally of the jib, forming arms of equal length on opposite sides of the vertical plane containing the longitudinal axis of the jib. A second anchorage for pulley blocks comprises a cross member 6, in the form of a beam, which is horizontally disposed transversely of the deck 4 at an elfective height therefrom. The cross member is supported at its ends by two upright columns 7 secured to the deck and so located that the center of the cross member is substantially directly above the trunnion 3.

Single-sheave pulley blocks are pivotally anchored each to a dilferent point on the outrigger 5 and cross member 6, these pulley blocks being arranged in groups, namely two groups P1 and P2, which are symmetrically disposed relative to the axis of the jib, with one group on each arm of the outrigger; and two groups P3 and P4 which are symmetrically disposed about the center of the cross member (FIG. 2). The groups P1 and P2 each comprise three pulley blocks 8, 9 and 10, and the groups P3 and P4 each comprise four pulley blocks 11, 12, 13 and 14, the pulley bloc-ks in groups P1 and P2 being spaced apart at smaller intervals than the pulley blocks in groups P3 and P4.

The jib 1 is supported, lufred and slewed by means of two ropes 15 and 16 which cooperate respectively with the pulley blocks in groups P1, P3 and P2, and P4, one end of each rope being wound in the same direction around the winding drum 17 of a luffing winch, and the. other ends being wound in opposite directions around the winding drum 18 of a slewing winch. The drums 17 and 18 are shown in FIG. 1, from which the other details of the winches have been omitted.

As shown in the drawings, each of the ropes 15 and 16 pass from the drum 17 of the lufiing winch to, and around, the appropriate pulley block 11 whence it is progressively reeved around the pulley blocks 8, 12, 9, 13 and 10 and then around the pulley block 14 to the drum 18 of the slewing winch. Thus the ropes 15 and 16 define a plurality of rope reaches comprising two groups of reaches which extend between the outrigger 5 and cross member 6, these groups being disposed one on each side of the vertical plane containing the longitudinal axis of the jib and each group having rope reaches which, because of the particular arrangements of the pulley blocks described, are mutually divergent as from the outrigger to the cross member.

The means for supporting, raising and lowering loads are shown in the drawings simply as a load hook 19 attached to a cable 20 (indicated by chain-dotted lines) which passes over a pulley 21 to a cargo winch (not shown). Alternatively and preferably, however, such means may be as disclosed in the specification of my British Patent No. 1,049,863 or the specification of my copending British Patent application No. 10,086/65.

In operation of the crane during lufiing, the winding drum 17 of the lufiing winch is rotated simultaneously to take in or pay out equal lengths of the ropes 15 and 16, thereby respectively raising or lowering the jib, while the winding drum 18of the slewing winch is held stationary. Similarly, during slewing, the winding drum 18 of the slewing winch is rotated simultaneously to take in and pay out equal lengths of the ropes 15 and 16 respectively, dependent of course upon the direction of slewing, while the drum 17 of the luffing winch is held stationary.

However, instead of the separate lufiing and slewing operations just described, the jib can simultaneously be lutfed and slewed by suitably cooperating the lufiing and slewing winches.

In comparison with previously proposed jib cranes, a jib crane constructed in accordance with the present invention possesses improved characteristics of stability during slewing whereby undesirable movement of the jib is reduced, especially at or near the extreme limits of slewing, for example, when the jib of a ships crane is moved to its farthest outboard position. Moreover, the arrangement of the pulley blocks, as hereinbefore described, spreads the load on the anchorages, thus providing an opportunity to increase the safety factor at the anchorages. Further, particularly by employing single-sheave pulley blocks, the pulleys thereof are permitted to align themselves with their associated ropes in an improved manner with a consequent reduction in wear which may result from chafing between the ropes themselves and between the ropes and pulley blocks.

Various modifications within the scope of the invention may be made to the crane just described.

For instance, although in the drawing the ropes 15 and 16 pass from the lufiing winch to the innermost pulley blocks 11 and from the outermost pulley blocks 14 to the slewing winch, the ropes may be otherwise arranged with respect to the winches, for example, the ropes may pass from the lufling winch to the pulley blocks 14, and from the pulley blocks 11 to the slewing winch. Also, for increased loading capacity of the crane, certain of the aforementioned single-sheave pulley blocks may be replaced by pulley blocks each having more than one sheave, the ropes being reeved accordingly, and, additionally or alternatively, the number of pulley blocks and associated rope reaches may be increased up to any limit determined by practical considerations. Further, the pulley blocks need not necessarily be arranged in line on each anchorage as illustrated.

Having described my invention, I claim:

1. A jib crane including a jib mounted at one end on a base for lufiing and slewing movements relative to the base, a first anchorage on the jib adjacent the free end thereof and extending laterally on both sides thereof, a second anchorage fixed relative to said base and disposed transversely of the jib above the mounted end of the jib, pulley means anchored to said anchorages at spaced intervals therealong, winch means, and ropes operatively associated with winch means and cooperating with said pulley means to etfect said lufling and slewing movements, said ropes being reeved back and forth around and between the pulley means anchored to said first and second anchorages to form between said anchorages a plurality of rope reaches which are disposed on both sides of the vertical plane containing the longitudinal axis of the jib and which substantially traverse in zig-zag manner the quadrilateral space defined by the ends of said anchorages, said pulley means being so spaced along said anchorages that the rope reaches on each side of said plane include reaches which diverge from each other from said first to said second anchorage.

2. A jib crane according to claim 1, wherein said ropes have their ends attached to said winch means in such a way as to effect said lufiing and slewing movements of the jib, the ropes passing from the winch means to and around pulleys of said pulley means on said second anchorage, Wherefrom the ropes form said plurality of reaches between said anchorages.

3. A jib crane according to claim 1, wherein said rope reaches on each side of said vertical plane are defined by a single rope having its ends attached to said winch means in such a way as to effect said luffing and slewing movements of the jib.

4. A jib crane according to claim 3, wherein each said rope has its ends wound around the winding drums respectively of luffing and slewing winches.

5. A jib crane according to claim 4, wherein said ropes each have one end wound in the same direction around the winding drum of a luffing winch, the other ends being wound in opposite directions around the winding drum References Cited UNITED STATES PATENTS 4/1958 Banks 2123 10 /1962 Trevisan 212-3 FOREIGN PATENTS 100,316 11/ 1964 Denmark.

HARVEY C. HORNSBY, Primary Examiner U.S. 01. x11, 212 3, 144 

